Asparagine-linked Oligosaccharides Research Articles

Comprehensive N-glycosylation mapping of envelope glycoprotein from tick-borne encephalitis virus grown in human and tick cells

Tick-borne encephalitis virus (TBEV) is the causative agent of severe human neuroinfections that most commonly occur after a tick bite. N-Glycosylation of the TBEV envelope (E) glycoprotein is critical for virus egress in mammalian cells, but not in tick cells. In addition, glycans have been reported to mask specific antigenic sites from recognition by neutralizing antibodies. In this regard, the main purpose of our study was to investigate the profile of N-glycans linked to the E protein of TBEV when grown in human neuronal cells and compare it to the profile of virus grown in tick cells. Mass spectrometric analysis revealed significant differences in these profiles. High-mannose glycan with five mannose residues (Man5GlcNAc2), a complex biantennary galactosylated structure with core fucose (Gal2GlcNAc2Man3GlcNAc2Fuc), and a group of hybrid glycans with the composition Gal0-1GlcNAc1Man3-5GlcNAc2Fuc0-1 were confirmed as the main asparagine-linked oligosaccharides on the surface of TBEV derived from human neuronal cells. The observed pattern was supported by examination of the glycopeptides, providing additional information about the glycosylation site in the E protein. In contrast, the profile of TBEV grown in tick cells showed that paucimannose (Man3-4 GlcNAc2Fuc0-1) and high-mannose structures with five and six mannoses (Man5-6GlcNAc2) were major glycans on the viral surface. The reported results complement existing crystallography and cryoelectron tomography data on the E protein structure and could be instrumental for designing carbohydrate-binding antiviral agents active against TBEV.

Essential Functions of Glycans in Human Epithelia Dissected by a CRISPR-Cas9-Engineered Human Organotypic Skin Model.

SummaryThe glycome undergoes characteristic changes during histogenesis and organogenesis, but our understanding of the importance of select glycan structures for tissue formation and homeostasis is incomplete. Here, we present a human organotypic platform that allows genetic dissection of cellular glycosylation capacities and systematic interrogation of the roles of distinct glycan types in tissue formation. We used CRISPR-Cas9 gene targeting to generate a library of 3D organotypic skin tissues that selectively differ in their capacity to produce glycan structures on the main types of N- and O-linked glycoproteins and glycolipids. This tissue library revealed distinct changes in skin formation associated with a loss of features for all tested glycoconjugates. The organotypic skin model provides phenotypic cues for the distinct functions of glycoconjugates and serves as a unique resource for further genetic dissection and identification of the specific structural features involved. The strategy is also applicable to other organotypic tissue models.

Characterization of MiFUT11 from Mangifera indica L.: A functional core α1,3-fucosyltransferase potentially involved in the biosynthesis of immunogenic carbohydrates in mango fruit

In higher plants, asparagine-linked oligosaccharides (N-glycans) in glycoproteins carry unique carbohydrate epitopes, namely, a core α1,3-fucose and/or a β1,2-xylose, which are common determinants responsible for the cross-reactivity of plant glycoproteins due to their strong immunogenicity. While these determinants and the relevant genes have been well characterized for herbaceous plants, information concerning whether many food plants cross-react with airborne pollens is not available. In this paper, we report on the characterization of a novel core α1,3-fucosyltransferase gene identified from Mangifera indica L., one of the major plants potentially related to food allergy. Based on sequence information of plant homologues, we amplified a candidate cDNA (MiFUT11) from pericarp tissue. An in vitro assay demonstrated that the recombinant MiFUT11 protein transfers a fucose unit onto both non-fucosylated and core α1,6-fucosylated oligosaccharides. A glycoform analysis using MALDI-TOF mass spectrometry showed that the introduction of the MiFUT11 cDNA increased the production of a core α1,3- and α1,6-fucosylated pauci-mannosidic oligosaccharide in Spodoptera Sf21 cells. Our findings suggest that MiFUT11 is a functional core α1,3-fucosyltransferase gene that is involved in the assembly of cross-reactive N-glycans in mango fruit.

N-glycans of the microalga Chlorella vulgaris are of the oligomannosidic type but highly methylated

Microalgae of the genus Chlorella vulgaris are candidates for the production of lipids for biofuel production. Besides that, Chlorella vulgaris is marketed as protein and vitamin rich food additive. Its potential as a novel expression system for recombinant proteins inspired us to study its asparagine-linked oligosaccharides (N-glycans) by mass spectrometry, chromatography and gas chromatography. Oligomannosidic N-glycans with up to nine mannoses were the structures found in culture collection strains as well as several commercial products. These glycans co-eluted with plant N-glycans in the highly shape selective porous graphitic carbon chromatography. Thus, Chlorella vulgaris generates oligomannosidic N-glycans of the structural type known from land plants and animals. In fact, Man5 (Man5GlcNAc2) served as substrate for GlcNAc-transferase I and a trace of an endogenous structure with terminal GlcNAc was seen. The unusual more linear Man5 structure recently found on glycoproteins of Chlamydomonas reinhardtii occurred - if at all - in traces only. Notably, a majority of the oligomannosidic glycans was multiply O-methylated with 3-O-methyl and 3,6-di-O-methyl mannoses at the non-reducing termini. This modification has so far been neither found on plant nor vertebrate N-glycans. It’s possible immunogenicity raises concerns as to the use of C. vulgaris for production of pharmaceutical glycoproteins.

Long-term correction of hemophilia A mice following lentiviral mediated delivery of an optimized canine factor VIII gene.

Current therapies for hemophilia A include frequent prophylactic or on-demand intravenous factor treatments which are costly, inconvenient and may lead to inhibitor formation. Viral vector delivery of factor VIII (FVIII) cDNA has the potential to alleviate the debilitating clotting defects. Lentiviral-based vectors delivered to murine models of hemophilia A mediate phenotypic correction. However, a limitation of lentiviral-mediated FVIII delivery is inefficient transduction of target cells. Here, we engineer a feline immunodeficiency virus (FIV) -based lentiviral vector pseudotyped with the baculovirus GP64 envelope glycoprotein to mediate efficient gene transfer to mouse hepatocytes. In anticipation of future studies in FVIII-deficient dogs, we investigated the efficacy of FIV-delivered canine FVIII (cFVIII). Codon-optimization of the cFVIII sequence increased activity and decreased blood loss as compared to the native sequence. Further, we compared a standard B-domain deleted FVIII cDNA to a cDNA including 256 amino acids of the B-domain with 11 potential asparagine-linked oligosaccharide linkages. Restoring a partial B-domain resulted in modest reduction of endoplasmic reticulum (ER) stress markers. Importantly, our optimized vectors achieved wild-type levels of phenotypic correction with minimal inhibitor formation. These studies provide insights into optimal design of a therapeutically relevant gene therapy vector for a devastating bleeding disorder.

Detection of phosphoglucomutase-3 deficiency by lectin-based flow cytometry

Detection of phosphoglucomutase-3 deficiency by lectin-based flow cytometry

Hepatic aberrant glycosylation by N-acetylglucosaminyltransferase V accelerates HDL assembly.

Glycosylation is involved in various pathophysiological conditions. N-Acetylglucosaminyltransferase V (GnT-V), catalyzing β1-6 branching in asparagine-linked oligosaccharides, is one of the most important glycosyltransferases involved in cancer and the immune system. Recent findings indicate that aberrant N-glycan structure can modify lipid metabolism. In this study, we investigated the effects of aberrant glycosylation by GnT-V on high-density lipoprotein cholesterol (HDL) assembly. We used GnT-V transgenic (Tg) mice and GnT-V Hep3B cell (human hepatoma cell line) transfectants. The study also included 96 patients who underwent medical health check-ups. Total serum cholesterol levels, particularly HDL-cholesterol (HDL-C) levels, were significantly increased in Tg vs. wild-type (WT) mice. Hepatic expression of apolipoprotein AI (ApoAI) and ATP-binding cassette subfamily A member 1 (ABCA1), two important factors in HDL assembly, were higher in Tg mice compared with WT mice. ApoAI and ABCA1 were also significantly elevated in GnT-V transfectants compared with mock-transfected cells. Moreover, ApoAI protein in the cultured media of GnT-V transfectants was significantly increased. Finally, we found a strong correlation between serum GnT-V activity and HDL-C concentration in human subjects. Multivariate logistic analyses demonstrated that GnT-V activity was an independent and significant determinant for serum HDL-C levels even adjusted with age and gender differences. Further analyses represented that serum GnT-V activity had strong correlation especially with the large-size HDL particle concentration. These findings indicate that enhanced hepatic GnT-V activity accelerated HDL assembly and could be a novel mechanism for HDL synthesis.

Identification and Characterization of a Novel Prokaryotic Peptide: N-GLYCOSIDASE FROM ELIZABETHKINGIA MENINGOSEPTICA

Peptide:N-glycosidase (PNGase) F, the first PNGase identified in prokaryotic cells, catalyzes the removal of intact asparagine-linked oligosaccharide chains from glycoproteins and/or glycopeptides. Since its discovery in 1984, PNGase F has remained as the sole prokaryotic PNGase. Recently, a novel gene encoding a protein with a predicted PNGase domain was identified from a clinical isolate of Elizabethkingia meningoseptica. In this study, the candidate protein was expressed in vitro and was subjected to biochemical and structural analyses. The results revealed that it possesses PNGase activity and has substrate specificity different from that of PNGase F. The crystal structure of the protein was determined at 1.9 Å resolution. Structural comparison with PNGase F revealed a relatively larger glycan-binding groove in the catalytic domain and an additional bowl-like domain with unknown function at the N terminus of the candidate protein. These structural and functional analyses indicated that the candidate protein is a novel prokaryotic N-glycosidase. The protein has been named PNGase F-II.

Expression of Fucosyltransferase 8 Is Associated with an Unfavorable Clinical Outcome in Non-Small Cell Lung Cancers

Objecitive: Fucosyltransferase 8 (FUT8), the only enzyme responsible for the core α1,6-fucosylation of asparagine-linked oligosaccharides of glycoproteins, is a vital enzyme in cancer development and progression. We examined FUT8 expression in non-small cell lung cancers (NSCLCs) to analyze its clinical significance. We also examined the expression of guanosine diphosphate-mannose-4,6-dehydratase (GMD), which is imperative for the synthesis of fucosylated oligosaccharides. Methods: Using immunohistochemistry, we evaluated the expression of FUT8 and GMD in relation to patient survival and prognosis in potentially curatively resected NSCLCs. Results: High expression of FUT8 was found in 67 of 129 NSCLCs (51.9%) and was significantly found in non-squamous cell carcinomas (p = 0.008). High expression of FUT8 was associated with poor survival (p = 0.03) and was also a significant and independent unfavorable prognostic factor in patients with potentially curatively resected NSCLCs (p = 0.047). High expression of GMD was significantly associated with high FUT8 expression (p = 0.04). Conclusions: High expression of FUT8 is associated with an unfavorable clinical outcome in patients with potentially curatively resected NSCLCs, suggesting that FUT8 can be a prognostic factor. The analysis of FUT8 expression and its core fucosylated products may provide new insights for the therapeutic targets of NSCLCs.

Predominant expression of N-acetylglucosaminyltransferase V (GnT-V) in neural stem/progenitor cells

Neural stem/progenitor cells (NPCs) express a variety of asparagine-linked oligosaccharide chains, called N-glycans, on the cell surface, and mainly produce hybrid-type and complex-type N-glycans. However, the expression profiles and roles of N-acetylglucosaminyltransferase-V (GnT-V), an enzyme that forms β1,6-branched N-glycans, in NPCs remain unknown. In this study, cultured NPCs were prepared from adult or embryo cortex, and were maintained as either proliferating NPCs or differentiated cells in vitro. Analysis using reverse-transcriptase polymerase chain reaction, Western blot and lectin blot revealed that GnT-V and its reaction products were distinctly expressed in proliferating NPCs; moreover expression of GnT-V and its reaction products were markedly diminished in differentiated cells. In brain slices, many GnT-V-positive neurogenic cells were detected throughout the cerebral cortex on embryonic day 13, while only a few doublecortin (Dcx)- and GnT-V-double positive NPCs were detected around the subventricular zone of the lateral ventricle in the adult brain. However, in the mice in which motor function was spontaneously recovered after cryoinjury to the motor cortex, many Dcx- and GnT-V-double positive NPCs were found to have accumulated around the brain lesion of the adult cerebral cortex compared with the mice in which the function did not recover. These results indicate that GnT-V expression is under rigorous control during NPC differentiation. Furthermore, expression of GnT-V and its reaction products in NPCs may be necessary for the functional recovery after brain injury, and could be used as a marker for visualization of NPCs.

Evaluation of desialylation during 2-amino benzamide labeling of asparagine-linked oligosaccharides

Labeling of released asparagine-linked (N-linked) oligosaccharides from glycoproteins is commonly performed to aid in the separation and detection of the oligosaccharide. Of the many available oligosaccharide labels, 2-amino benzamide (2-AB) is a popular choice for providing a fluorescent product. The derivatization conditions can potentially lead to oligosaccharide desialylation. This work evaluated the extent of sialic acid loss during 2-AB labeling of N-linked oligosaccharides released from bovine fetuin, polyclonal human serum immunoglobulin G (IgG), and human α1-acid glycoprotein (AGP) as well as of sialylated oligosaccharide reference standards and found that for more highly sialylated oligosaccharides the loss is greater than the <2% value commonly cited. Manufacturers of glycoprotein biotherapeutics need to produce products with a consistent state of sialylation and, therefore, require an accurate assessment of glycoprotein sialylation.

Expression, Purification, and Characterization of Endo-β-N-Acetylglucosaminidase H Using Baculovirus-Mediated Silkworm Protein Expression System

Endo-β-N-acetylglucosaminidase (Endo H) from Streptomyces plicatus hydrolyzes the core di-GlcNAc units of asparagine-linked oligosaccharides and is regarded as an important tool for glycobiology research. In the present study, we established a large-scale system to produce secreted Endo H using a silkworm-baculovirus expression system (silkworm-BES). The recombinant Endo H purified from silkworm hemolymph had activity comparable to that from recombinant Escherichia coli. As well as its well-characterized substrate RNase B, the Endo H from silkworm-BES was able to deglycosylate the high-mannose glycoproteins from silkworm hemolymph. Interestingly, the secretion amount of recombinant Endo H was significantly varied among the different silkworm strains, which could provide valuable information for larger-scale protein productions from silkworm-BES.

Lack of Galactosylation Enhances the Pathogenic Activity of IgG1 but Not IgG2a Anti-Erythrocyte Autoantibodies

IgG bears asparagine-linked oligosaccharide side chains in the Fc region. Variations in their extent of galactosylation and sialylation could modulate IgG Fc-dependent effector functions, and hence Ab activity. However, it has not yet been clarified whether the pathogenic potential of IgG autoantibodies is consistently enhanced by the absence of galactose residues per se or the lack of terminal sialylation, which is dependent on galactosylation. Moreover, it remains to be defined whether the increased pathogenicity of agalactosylated IgG is related to activation of the complement pathway by mannose-binding lectin, as suggested by in vitro studies. Using a murine model of autoimmune hemolytic anemia, we defined the contribution of galactosylation or sialylation to the pathogenic activity of IgG1 and IgG2a anti-erythrocyte class-switch variants of 34-3C monoclonal autoantibody. We generated their degalactosylated or highly sialylated glycovariants and compared their pathogenic effects with those of highly galactosylated or desialylated counterparts. Our results demonstrated that lack of galactosylation, but not sialylation, enhanced the pathogenic activity of 34-3C IgG1, but not IgG2a autoantibodies. Moreover, analysis of in vivo complement activation and of the pathogenic activity in mice deficient in C3 or IgG FcRs excluded the implication of mannose-binding lectin-mediated complement activation in the enhanced pathogenic effect of agalactosylated IgG1 anti-erythrocyte autoantibodies.

Negative expression of N-acetylglucosaminyltransferase V in oral squamous cell carcinoma correlates with poor prognosis

N-acetylglucosaminyltransferase V (GnT-V), an enzyme with a key role in the branching of asparagine-linked oligosaccharides, is strongly linked to tumor invasion and metastasis of many solid tumors. Here we searched for correlations between the clinical features of patients with oral squamous cell carcinoma (OSCC) and GnT-V expression in the tumor, and we studied the feasibility of using GnT-V as a marker for oral cancer prognosis. Samples from 68 patients with OSCC were examined by immunohistochemistry using antibodies against GnT-V. Correlations between the expression level of GnT-V in the tumor and patient clinical features were statistically analyzed. Positive GnT-V expression was found in 48 cases (70.6%), and negative GnT-V expression was found in 20 cases (29.4%). Negative GnT-V expression was associated with mode of invasion by multiple logistic regression analysis (OR: 3.605; P = 0.048). Biological characteristics of tumors and the Ki-67 labeling index were higher in tumors with negative GnT-V expression than in those with positive GnT-V expression, although the difference was not significant (P = 0.176). Patients with negative GnT-V expression had significantly shorter survival than those with tumors having positive GnT-V expression (5-year survival rate, 58.2% and 86.5%, respectively; P = 0.025). Negative GnT-V expression was a significant unfavorable prognostic factor for OSCC (hazard ratio, 4.246; P = 0.045). The loss of GnT-V expression is a likely indicator of tumors with high potential of tumor invasion and poor prognosis in OSCC patients.

The GlycoFilter: A Simple and Comprehensive Sample Preparation Platform for Proteomics, N-Glycomics and Glycosylation Site Assignment

Current strategies to study N-glycoproteins in complex samples are often discrete, focusing on either N-glycans or N-glycosites enriched by sugar-based techniques. In this study we report a simple and rapid sample preparation platform, the GlycoFilter, which allows a comprehensive characterization of N-glycans, N-glycosites, and proteins in a single workflow. Both PNGase F catalyzed de-N-glycosylation and trypsin digestions are accelerated by microwave irradiation and performed sequentially in a single spin filter. Both N-glycans and peptides (including de-N-glycosylated peptides) are separately collected by filtration. The condition to effectively collect complex and heterogeneous N-glycans was established on model glycoproteins, bovine ribonuclease B, bovine fetuin, and human serum IgG. With this platform, the N-glycome, N-glycoproteome and proteome of human urine and plasma were characterized. Overall, a total of 865 and 295 N-glycosites were identified from three pairs of urine and plasma samples, respectively. Many sites were defined unambiguously as partially occupied by the detection of their nonsugar-modified peptides (128 from urine and 61 from plasma), demonstrating that partial occupancy of N-glycosylation occurs frequently. Given the likely high prevalence and variability of partial occupancy, glycoprotein quantification based exclusively on deglycosylated peptides may lead to inaccurate quantification.

Expression of N-acetylglucosaminyltransferase V in the subserosal layer correlates with postsurgical survival of pathological tumor stage 2 carcinoma of the gallbladder

N-Acetylglucosaminyltransferase V (GnT-V), an enzyme that catalyzes the β1-6 branching of N-acetylglucosamine on asparagine-linked oligosaccharides of cellular proteins, enhances the malignant behaviors of carcinoma cells in experimental models. The aim of this study was to determine clinical significance of GnT-V expression in human pT2 gallbladder carcinoma with simple in vitro experiments. Ninety patients with pT2 gallbladder carcinoma were included for this study. The in vitro and in vivo biological effects of GnT-V were investigated using gallbladder carcinoma cells with variable GnT-V expression levels induced by a small interfering RNA. Of the 90 cases, 57 showed positive staining and the remaining 33 demonstrated negative staining, the subcellular localization in the 57 cases was classified into the granular-type in 31 cases and the diffuse-type in 26 cases. In 76 cases with curative resection, postsurgical survival was significantly poorer in those showing positive staining than in those showing negative staining (P=0.028). In all of the 76 cases, postsurgical recurrence was significantly more frequent in those showing diffuse-type localization than in those showing negative staining. Experimental analyses demonstrated that the down-regulation of GnT-V expression in gallbladder carcinoma cells induced suppression of cell growth in vitro. The expression levels of GnT-V in the cells were highly correlated with the rapid in vivo growth coupled with the enhanced angiogenesis, and the tendency to form liver metastasis. GnT-V expression in the subserosal layer of pT2 gallbladder carcinoma is correlated with the aggressiveness of the disease.

Downregulation of the GnT-V gene inhibits metastasis and invasion of BGC823 gastric cancer cells

Metastatic and invasive potential is a barrier to the successful treatment of gastric cancer. N-acetylgluco-saminyltransferase V (GnT-V), a key enzyme catalyzing the formation of 1,6 N-acetylglucosamine (GlcNAc), has been demonstrated to display a distinct function in different types of tumors. The aim of this study was to investigate the role of GnT-V in the invasive potential of BGC823 human gastric cancer cells invitro and the possible underlying mechanism. GnT-V was downregulated in BGC823 cells by oligo-siRNA transfection. Cell proliferation and invasiveness were assessed by CCK-8 assay, Tunel assay, scratch-wound assay as well as transwell assay. The products of GnT-V, β1-6 branching of asparagine-linked oligosaccharides, were determined by L-PHA lectin blot analysis. The expression of EGFRs, E-cadherin/vimentin and MMP-2/MMP-9 was analyzed both at the mRNA and protein levels. The results showed that downregulation of GnT-V decreased proliferation and the metastatic/invasive potential of BGC823 cells. The expression of EGFRs, E-cadherin/vimentin and MMP-9, molecules related to cancer metastasis and invasion in various tumors, were influenced correspondingly. These findings suggest that downregulation of GnT-V inhibited cell metastasis and invasion of BGC823 cells via EGFR signaling-initiated EMT phenotype and MMP-9 expression. These results provide a novel mechanism to explain the role of GnT-V in cell metastasis and invasion.

High expression of N-acetylglucosaminyltransferase IVa promotes invasion of choriocarcinoma

Background:Gestational trophoblastic diseases (GTDs) are related to trophoblasts, and human chorionic gonadotropin (hCG) is secreted by GTDs as well as normal placentas. However, the asparagine-linked sugar chains on hCG contain abnormal biantennary structures in invasive mole and choriocarcinoma, but not normal pregnancy or hydatidiform mole. N-acetylglucosaminyltransferase-IV (GnT-IV) catalyses β1,4-N-acetylglucosamine branching on asparagine-linked oligosaccharides, which are consistent with the abnormal sugar chain structures on hCG.Methods:We investigated GnT-IVa expression in GTDs and placentas by immunohistochemistry, western blot, and RT–PCR. We assessed the effects of GnT-IVa knockdown in choriocarcinoma cells in vitro and in vivo.Results:The GnT-IVa was highly expressed in trophoblasts of invasive mole and choriocarcinoma, and moderately in extravillous trophoblasts during the first trimester, but not in hydatidiform mole or other normal trophoblasts. The GnT-IVa knockdown in choriocarcinoma cells significantly reduced migration and invasive capacities, and suppressed cellular adhesion to extracellular matrix proteins. The extent of β1,4-N-acetylglucosamine branching on β1 integrin was greatly reduced by GnT-IVa knockdown, although the expression of β1 integrin was not changed. In vivo studies further demonstrated that GnT-IVa knockdown suppressed tumour engraftment and growth.Conclusion:These findings suggest that GnT-IVa is involved in regulating invasion of choriocarcinoma through modifications of the oligosaccharide chains of β1 integrin.

Abstract A41: Dasatinib regulation of N-glycans induce anticancer activity in hematological and solid tumor malignancies.

Abstract Glycans are carbohydrates covalently bound to proteins or lipids. Changes in their content and structure, particularly in asparagine-linked oligosaccharides, contribute to a variety of events during malignant transformation. These include the loss of cell-matrix adhesion, migration, invasion, metastasis, and evasion of cell death. High mannose glycans are not commonly present on the surfaces of normal mammalian cells or in serum, yet they play important roles in cancer cell biology. Therefore, modulation of glycan expression with drugs offers a promising therapeutic approach for various hematological and solid tumor cancers, several of which disproportionally afflict minority populations. Dasatinib, a dual inhibitor of Src and Abl tyrosine kinase, is used to investigate in vitro anti-cancer activity in several cancer cell lines: Jurkat lymphoblastic leukemia, Raji lymphoblastic lymphoma, SiHa cervical cancer, H1650 non small cell lung cancer, PC3N prostate cancer, SKOV3 ovarian cancer, and MCF7 breast cancer. To address how the carbohydrate moieties of the cancer cells are affected during treatment, the glycan profiles from treated cells are compared to non-treated cells and normal controls and analyzed by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). PCR arrays are used to profile glycosylation enzyme gene expression changes due to dasatinib-induced cytotoxicity. Protein expression arrays are used to investigate Src and Abl receptor tyrosine kinase signaling cascades. The results presented here demonstrate new evidence of glycosylation expression changes and the related mechanisms of their anticancer activity. Regulation of glycosylation is a promising therapeutic strategy for inducing anticancer activity through cell arrest, apoptosis, and autophagy. Citation Format: Mary R. Saunders, L. Renee Ruhaak, Cynthia Williams, David J. Olivos, Carol Stroble, Hyun Joo An, Suzanne Miyamoto, Carlito B. Lebrilla, Kit S. Lam. Dasatinib regulation of N-glycans induce anticancer activity in hematological and solid tumor malignancies. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr A41.

Sialylation Determines the Nephritogenicity of IgG3 Cryoglobulins

Monoclonal 6-19 IgG3 anti-IgG2a rheumatoid factor derived from lupus-prone MRL-Fas(lpr) mice can induce GN and cryoglobulinemia, but the features that confer nephritogenic potential are not completely understood. Asparagine-linked oligosaccharide chains of 6-19 IgG3 mAb are poorly galactosylated and hardly sialylated, possibly contributing to the pathogenic potential of 6-19 IgG3 rheumatoid factors. Here, we used the 6-19 model of cryoglobulin-associated GN to define the relative contributions of galactosylation and sialylation, in relation to cryoglobulin activity, to the nephritogenic potential of IgG3 antibodies. We generated one highly sialylated and two distinct more galactosylated 6-19 IgG3 rheumatoid factor variants. Although the mere extent of galactosylation had no effect on either the cryogenic and nephritogenic activities of 6-19 IgG3 rheumatoid factor, terminal sialylation attenuated the nephritogenic potential of 6-19 IgG3 by limiting its cryoglobulin activity. These data suggest a protective role of IgG sialylation against the development of cryoglobulin-mediated GN, highlighting the anti-inflammatory activity of sialylated IgG antibodies.